ES2207766T3 - FEMUR NECK ENDOPROTESIS FOR AN ARTIFICIAL CHAIN ARTICULATION. - Google Patents

Abstract

Thigh endoprosthesis comprises: a sleeve (1') cementless in the upper region of a femur within the Trochanter majors, the outer side of the sleeve being partially covered with a three dimensional network (9'); and a sleeve end formed as stem end (30') partially covered with a three dimensional network.

Description

Femoral neck endoprosthesis for a artificial hip joint.

A femoral neck stent is described for an artificial hip joint, which is a alternative of the femoral neck stent according to the Patent German 196 01 340.

For the treatment of a joint head of destroyed hip, where considerable sensations result painful and aggravating functional limitations of the joint, essentially two have prevailed over the past decades therapy possibilities:

On the one hand, it is possible to provide patients an orthotic, that is, an external support device. further from the fact that this possibility of supply is totally unacceptable as cosmetic, it is also, in terms of technique supply, simply lower than optimal.

As another possibility, very widespread, is planned to provide patients with a stent, that is, a stent of hip shaft, in which a shaft is introduced in the bone marrow space, emptied previously, of the femur and is fixed there without cement, or, using a cement. On the side next, a similar stent then presents the possibility of union with an artificial articulated ball.

Just the last possibility is defended intensely in the patent literature. See, in this regard, for example, document DE 94 12 408 U1.

Between one or another of the stent stents of Hip proposals in the patent literature, there are some principles that are very promising in terms of long-term stability term in the patient's body. However, sooner or later, by example, after 10 to 15 years, it should be noted that the stent is subject to wear, which leads to the need from, through a revision intervention, remove the stent implanted and replace it with a new one. This is not done. totally without problems, since, in the first implantation, by resecting and emptying the bone marrow space, you have a considerable part of natural bone material has been removed. The material removed before may be missing later in an intervention Review This has to be taken into account especially when the patients are relatively young, in which we must start from which, in the course of their life, must be subjected to at least one Review intervention

A stent that produces a resection of natural material of the bone a little smaller than the stents of known asxyl coxal has been known from DE 27 24 234 C2 The prosthesis part described there is implanted in the area superior of a femur, but under the trochanter, without a asylum in the bone marrow space. This prosthesis, also called "pressure disc prosthesis" covers, essentially with a nearby pressure plate, cortical tissue of the resected femur in the area of the coxal joint head removed. It's tight with a pressure plate, which rests laterally on the femur, so that all the mechanical forces between the stent and the femur be applied directly to the cortical tissue of the femur, whereby a mechanical effort on the spongy tissue that feels like inadmissible. Just one small amount of bone cement is necessary for clamping of the pressure disk in the near zone.

The philosophy of this prosthesis is based - such as described - in the assumption that the spongy substance The femur should be subjected to the least possible effort. Is achieved this in exchange for an extreme load of the cortical substance of the femur, being all the forces discharged from it and applied About this. According to today's knowledge, this is not corresponds, in no way, to the natural conditions of load.

WO 89/11837 shows, moreover, a prosthesis that works very similarly, in which the function of the next pressure plate, according to the document before cited, is perceived by the hip joint head, specially configured, which is provided, on the inner face, of an emptying, on which it is placed, by generating pressure, on the inside, the resected femur stump.

From documents FR 26 169 A1 and FR 26 74 122 A1 two prostheses are known in which, apparently, the load main must be absorbed by the spongy substance of the bone of the femur. In the first of the two documents mentioned is planned to screw a threaded bolt, which soon presents a Pluggable cone, in the spongy substance. This would produce, in short Short term, serious instability problems. In a second document of the two mentioned is attached a plate, which carries a plug-in cone, using a series of bone screws, arriving bone screws to spongy tissue. They are also here serious stability issues, since the natural spongy tissue it may be punctually loaded only a little in proportion to the cortical tissue of the femur bone.

Given this background scenario, it is therefore purpose of the present invention to indicate a stent of femur neck for a hip joint that, with respect to the application of force in the femur, in the case of resections of natural bone material that may become necessary only relatively fit considerably better than the prosthesis mentioned above.

Therefore, a femoral neck stent which, with respect to the application of force on the femur, in the case of resections of bone material natural that become necessary only relatively, fit considerably better than the prosthesis mentioned above.

To achieve this purpose, it is expected that the femoral neck stent present:

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a cap implantable without cement on top of a femur, under the trochanter major, being able to be attached its near end to a adapter for housing an artificial ball of joint, the outer surface of the bushing being covered at least partially by a three-dimensional spatial structure of open mesh network as well as

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one end of bushing curved towards the tail, configured as shaft end, which is at least partially covered with a spatial structure three-dimensional open mesh network, presenting the end of one step bushing, facing the tail, in a part of the transition to the shaft end.

Unlike German Patent 196 01 340 no according to the invention, there is provided a pull plate that acts along with a background that crosses the cortical bone tissue of the femur. This penetration causes a weakening of the bone of the femur.

The curved end of the bushing is, in the case present, that part where it is placed laterally on the cortical surface of natural spongy tissue. The implant according the invention must therefore be anchored so that it is "suspended in cantilever "in the spongy tissue of the femur neck, while that the implant according to German Patent 196 01 340 has a fixed or rotating point in the form of a traction plate.

The result, in the present case, is that the Femur bone is not weakened, from the outside, from any way. The structure is otherwise simpler than that according to German Patent 196 01 340. The coupling of a ball Artificial joint is performed in the same way with a corresponding adapter.

Other advantageous configurations result from the Subordinate claims.

The invention will be described in detail from an exemplary embodiment according to the only Figure of the He drew.

In the present invention, the 1 'socket It has a similar shape to the cap according to the Patent German 196 01 340. In the far part, however, the 1 'socket it becomes a tail end 30 'tail-shaped, that is, curved down, the curvature being dimensioned so that the outermost end of the shaft end 30 'rests on the lateral part of the inside of the femur.

The 1 'bushing is covered, as is the 30 'shaft end, with a three-dimensional spatial structure of 9 'open mesh net. The coupling of an artificial ball of 20 'joint is made with the 2', cone-shaped adapter double, in the same way as the one provided in the Patent German 196 01 340.

As you can clearly see, nowhere of the implant penetrates the cortical tissue of the femur bone 40 ', so that no weakening of the bone material takes place in this area. In those cases in which the femoral neck stent according to the invention, the consequence It is a more stable femur.

Claims (6)

1. Femoral neck endoprosthesis for a artificial hip joint, which presents

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a bushing (1 ') implantable at the top of a femur (40 '), below the greater trochanter, its proximal end (8 ') may be attached to a adapter (2 ') for housing an artificial ball of joint (20 '), the outer surface of the cap at least partially with a spatial structure three-dimensional open mesh network (9 '), as well as

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one end of bushing curved towards the tail, configured as shaft end (30 '), which is at least partially covered with a structure three-dimensional spatial mesh network open (9 '), presenting the cap end one step, facing the tail, in a part of the transition to the shaft end.

2. Femoral neck endoprosthesis according to Claim 1, wherein the bushing (1 '), from its end next (8 ') to the additional part of the curved shaft end (30 '), is configured so that it conically narrows. 3. Femoral neck endoprosthesis according to Claim 1 or 2, wherein the spatial network structure (9 ') is configured, on the head cap surfaces and of tail, as mesh is enough, with a width of mesh of 2 to 6 mm. 4. Femoral neck endoprosthesis according to one of claims 1 to 3, wherein the spatial structure network (9 ') is configured, in ventral and dorsal direction in the Cap surface, with fine mesh, with mesh widths between 1 and 2.5 mm. 5. Femoral neck endoprosthesis according to one of Claims 1 to 4, wherein the adapter (2 ') for the articulation ball (20 ') is essentially configured as double plug-in cone, with a circular flange (11 ') on both bases of the cone, being provided, in the proximal area of the bushing (1 '), a plug-in socket, conical shaped, corresponding to a plug-in cone. 6. Femoral neck endoprosthesis according to one of claims 1 to 5, wherein the surfaces, directed outward from the flange (11 ') of the adapter (2') they are covered with a three-dimensional space network structure of open mesh.